Title
Entropy and Optimal Compression of Some General Plane Trees.
Abstract
We continue developing the information theory of structured data. In this article, we study models generating d-ary trees (d ≥ 2) and trees with unrestricted degree. We first compute the entropy which gives us the fundamental lower bound on compression of such trees. Then we present efficient compression algorithms based on arithmetic encoding that achieve the entropy within a constant number of bits. A naïve implementation of these algorithms has a prohibitive time complexity of O(nd) elementary arithmetic operations (each corresponding to a number f(n, d) of bit operations), but our efficient algorithms run in O(n2) of these operations, where n is the number of nodes. It turns out that extending source coding (i.e., compression) from sequences to advanced data structures such as degree-unconstrained trees is mathematically quite challenging and leads to recurrences that find ample applications in the information theory of general structures (e.g., to analyze the information content of degree-unconstrained non-plane trees).
Year
DOI
Venue
2019
10.1145/3275444
ACM Trans. Algorithms
Keywords
Field
DocType
Arithmetic coding, plane recursive trees, random trees
Information theory,Data structure,Discrete mathematics,Upper and lower bounds,Elementary arithmetic,Time complexity,Data compression,Data model,Arithmetic coding,Mathematics
Journal
Volume
Issue
ISSN
15
1
1549-6325
Citations 
PageRank 
References 
0
0.34
13
Authors
3
Name
Order
Citations
PageRank
Zbigniew Golebiewski121.10
Abram Magner237.24
Wojciech Szpankowski31557192.33